Flooded Soil Fundamentals
This section provides an understanding of soil health and nutritional issues to consider when flood impacts productive farm land.
- General findings from the project from participating farms.
- An understanding of nutrient deficiencies and consequences on production and yield.
- A set of management activities to help replenish and enhance soil health in response to a flood event.
Impacts of Floods on Soil Health
A prolonged prescence of flood water can have incredibly negative impacts on the long term health of soils. This project aimed to explore those impacts across a variety of different production systems. The lack of oxygen combined with an influx of elements external to the system can cause a variety of issues for both short term and longer term soil health.
Tests were conducted on paired sites for each farm at depths of 0-10cm & 10-60cm. The analysis carried out included pH, organic carbon as well as both macro and micro nutrients.
- With areas that were affected by floods there was up to a 50% reduction in organic carbon levels. This identifies a significant impact on the long term sustainability of flooded soils.
- The calcium magnesium ratios were influenced by the floods in 30% of sites. This has significant impacts on soil drainage as well as the occurance of soil crusting.
- In 70% of the sites Phosphorous was lost both at surface levels as well as at depth. In the surface layer up to 120 mg/kg of P was lost as a result of floods.
- Up to 60% of sites suffered from losses of potassium ranging from 9-246 mg/kg in the 0-10cm range and 11-222 mg/kg in the 10-60cm range.
- Up to 70% of the sites saw Zinc losses averaging 6 mg/kg.
- Copper was also lost as a result of floods potentially proving costly if not accounted for in the following season.
When managing flooded soils its essential that soil tests are carried out prior to sowing the next crop. It is best to test at surface level as well as at depth in order to gain an accurate picture of your soils health. It may also be worth testing for any foreign pests that may have travelled in the flood waters such as nematodes as infections can prove damaging to a newly established crops or pastures.